Gun blast door



June 16, "1953 G. BUSSIERE ET AL GUN BLAST DOOR 5 Sheets-Sheet 1 Filed May 28, 1949 6. EU SSIERE 0. 6. JOHNSON JE- STRAUB INVENTORS WM/fi ATTORNEY June 16, 1953 e. sussnzm: ETAL GUN BLAST DOOR 3 Sheets-Sheet 2 Filed May 28, 1949 6. BUSS/ERE 0.6. JOHNSON J. E. STRAUB INVENTORS ATTORNEY June 16, 1953 e. BUSSIERE ETAL GUN BLAST DOOR Filed May 28, 1949 3 Sheets-Sheet 3 3/ -30 I I 2 6. SUSS/[RE 0. a. JOHNSON L E v 15. .STRAUB r\* INVENTORS FIG. 5 BY x ATTORNEY Patented June 16, 1953 "UNITED STATES PATENT OFFICE GUN BLAST noon George Bussiere, Los Angeles,--Quinton C Johnson, Torrance, and Joseph E. Straub, Manhattan Beach, Calif., assignors to North American Aviation, Inc.

1 Application May 28, 1949, Serial No. 95,896

10 Claims.

This invention pertains togun blast. doors and i mechanism for. operating the same.

The invention more particularly pertains to an arrangement for opening the doors quickly and for normally returning them within a predetermined period of time after cessation of fir- 1 ing of the gun.

It is an object of this invention to provide a-closure member for gun ports and like openings, and means for automatically operating these members.

It is, also ,an object of the present invention to provide means for automatically moving the closure members to open position upon initiation of firing, and to return them to the closed position upon cessation of firing, all without requiring the pilots attention.

'It is also an object of the present invention to provide time delay means incorporated in the door control circuit to avoid premature closing of the doors when the temperature of the guns has become elevated to a point where the possibility exists of inadvertent firing through heating effects.

It is a further object of the present invention ;-to. provide actuating mechanism for gun port doors-which is positivein action, rugged in construction, and controllable in a reliable manner.

Other objects of the present invention will be apparent from the following description taken together with the accompanying drawings, in

which:

Fig. 1 represents a schematic arrangement,

partlyin section, of a door in the closed position-with its associated actuation mechanism;

= Fig. 2 illustrates thedoor in open position;

Fig. 3 is a top plan view of the door actuating unit;

. Fig. 4 is a sectional view taken on line- 4-4 of Fig. 3; and

. Fig. 5 is. a circuit diagram illustrating the sub- .ject arrangement.

Referring to the.drawings, the arrangement comprises a door I pivotallymounted at 2 on the exterior surface of an aircraft and movable to and from/a closed position by means of lever arm 3. The arm 3 is operated by a mechanism presently to be described. Such mechanism includes a threaded fitting 4 pivotally mounted be- ..tween the bifurcated arms of .lever 3, such fituting receiving a bolt 5 which is splined to a ro- .-tatable shaft. 6.

Stop members I and B serve to limit the movement of lever 3. Shaft 6 is enerated-by means of. a gear wheel 9 integral therewith Ha bnsase l Worm 10 p 4 2 tivelyconnected to .shaft II which is driven by a sourceof power (not shown). Shaft H is movable toa position where worm I0 is out of engagement with gear 9 by means of a rotary type solenoid I2 pivoted at l3 and having an arm I4'pivoted thereto at [5 which in turn is pivotally. connected-at It to housing I! carrying shaft ll and worm I0. Accidental disengagement of the worm from the worm wheel is prevented by an over center arrangement, as represented by a-straight line between points I5 and It on the arm l4 with respect to the center of rotation l3 of the solenoid l2.

A spring l8 returns the solenoid arm and worm to gear-engaging position upon de-energization of the solenoid. Housing I1 is pivotally mounted at 19 on bracket 20. .Shaft H is mounted in open and closed positions.

. during flight.

housing ll bymeans of pivotal bearing 2|. A self-aligning bearing 22 supports the other end of shaft II on bracket 23 which formsa part of the .frame. .A pin and slot arrangement at 24 hassufficient lost motion to permit aligmnent of shaft 11 with shaft 25, and to permit shaft II to pivot upon bearing 2| when housing I! is -moved about its pivot I9 to disengage worm 10 from gear 9. Torque spring 26 is operatively connected at one end to shaft 6 and at the other end to the. frame to constantly urge the doors into open position so that upon disengagement point. Zlof the block 4 and the pivot 28 of the doorfitting as the shaftfi rotates the arm 3.

The actuator unitis further designed to avoid damage to the. mechanism which may readily occur from the corrosive efi'ects of the hot gases and the blast forces duringfiring. To this end only the chamber 29 in which the actuator arm 3 is positioned is exposed. This chamber is completely. sealed precluding the possibility of the remainder of the mechanism being afiected by the blastgases. with the resultant possibility .of malfunctioning or failure.

Thedoor. lis supported upon a housing. which forms a fol w ard. continuationof the. gun

blast tube (indicated in phantom) and provides means for excluding the blast gases from the adjacent portions of the structure. The housing is sealed except for the aperture through which the arm 3 extends. When the door is open a port is provided at 52 through which the gun may fire.

A deflector plate 53 is provided upon the arm 3, serving to deflect outwardly any projectile fired when the door is closed. The door is made of a frangible material sufiiciently durable for normal operation but designed to give way under the impact of a projectile. The deflector plate is arranged to direct the bullet against the door rather than permitting it to be indiscriminately ----defiected; rupturing the housing and damaging the adjacent structure and other equipment. 7

Power is supplied to the door-closing mechanism through the shaft 25, to move the door I to close port52, A friction clutch 54 is interposed between the power source and shaft 25, arranged to slip when the door is fully closed until the power provided to drive'the closing mechanism is discontinued.

The gun muzzle door-opening and -closing circuits are energized when the selector switch 30 is switched on and as the two-stage gun-firing switch 3| reaches the first position, the second stage serving to actuate the gun-firing mechanism. Engagement of the switch 3| energizes relay 32 which momentarily supplies current to relay 33 to complete the circuit 34 to energize the door solenoid l2 to release the door, allowing it to move to open position. The relay 33 is deenergized when the circuit is broken at relay 32, interrupting circuit 34.

The relay 32 operates a double pair of contacts, the second pair 36 serving to interrupt the circuit to the door-closing actuator 35, to be fully explained later. Upon cessation of firing, when the switch 3| is opened, relay 32 is deenergized allowing the contacts 36 to reengage to complete the circuit supplying power to a timer unit indicated at 31. The timer unit provides for a fixed time period to permit the gun to cool. The timer unit includes a constant speed motor 33 which drives a pair of cams 3940. Cam 39, at the end of the delay period, closes the switch 4| to energize the relay 49 to complete the circuit to the door-closing actuator 35 which drives shaft 25. The cam 40 subsequently opens a switch 42 to de-energize the relay 43 to interrupt the circuit supplying power to the timer motor 38 upon completion of the door-closing operation.

The timer circuit is controlled through relay 43, and a limit switch 44 on the door I prevents the relay 43 from being energized except when the door is in the open position. To prevent the door limit switch 44 from interrupting the timer cycle prematurely, the line 45 serves to maintain the relay 43 in energized condition and insures the continuing operation of the motor 39 until the switch 42 is opened by the cam 40.

When firing the guns while the ship is on the ground, as in testing or boresighting, it is necessary to prevent the doors from closing at the end of the usual timing period since the cooling rate is must slower than with the air blast encountered during flight, For this purpose a ground-air transfer relay 46 is provided to interrupt the circuit supplying current to the timer 31. A switch 41 which may be carried by, for instance, the landing gear for actuation by the weight of the ship when on the ground is opened to prevent the relay 46 from becoming energized.

A manual door-closing switch 48 is provided for the convenience of the ground crew and. after an adequate cooling period has elapsed the switch may be used to energize the relay 42 to complete the circuit supplying current to the door-closing actuator 35. In the event the doors are left open after ground operation the transfer relay 46 will be energized immedately upon the closing of the switch 41 upon takeoff. The normal operation of the timer unit 3! will then take over, completing the closing operation after the usual delay.

As a safety measure a momentary delay is provided to insure the door reaching its fully opened position prior to the actual firing of the gun. When the firing switch 3| reaches the second position a relay 55 of the time delay type is energized. The relay 55 closes the circuit 56 which energizes the gun firing solenoid. The relay 55 has a very short time delay characteristic, in the order of 50 milliseconds.

Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of this invention being limited only by the terms of the appended claims.

We claim:

1. In an aircraft having a port opening for a gun, a door for said opening and actuating means for said door, said door being made of material which is sufficient to withstand pressure to which it is subjected in flight, but is frangible upon impact of a bullet, link means connecting said door to said actuating means, said link means being located in the line of fire of the gun when the door is in closed position, and a plate on said link for deflecting any inadvertently fired bullet to the frangible door.

2. In an aircraft having a port opening for a gun, a door for said opening, actuating means for said door, said actuating means comprising spring means, motor-driven worm and gear means for tensioning said spring means, a rotary solenoid for moving said worm into and out of engagement with said gear, link means for connecting said rotary solenoid to said worm, and an over-dead-center arrangement for locking said worm in engaging position with said gear.

3. In an aircraft having a port opening for a gun, a door for said opening and actuator means for said door, said actuator means comprising a rotatable shaft driven by, a pilot-controlled source of power, a bolt fixed to said shaft to rotate therewith, a fitting on said bolt, and a lever pivotally connected at one end to said fitting and at the other end to said door, the pivotal connection of said lever to said fitting being an over-deadcenter arrangement for locking the door in either its open or closed position.

4. In an aircraft having a port opening for a gun, a door for said opening, and actuator means for said door, said actuator means comprising a pilot-controlled driving gear, a driven gear operatively associated with said driving gear, means operatively connecting said driven gear and said door, spring means constantly urging said door to open position, and means for disengaging said drivinggear from said driven gear to permit said spring to open said door.

5. In an aircraft having a port opening for a gun, a door for said opening, and actuating means for said door, said actuating means including a driving gear and a driven gear for urging said door into closed position, means for urging said door into open position, and means for disengaging said driving gear from said driven gear to permit operation of said door opening means.

6. In an aircraft having a port opening for a gun provided with a firing mechanism, a door for said opening, actuating means for said door, means connected to said firing mechanism for opening said door upon actuation of said firing mechanism to initiate firing of said gun, and time delay means connected to said firing mechanism and said door-actuating means for preventing closing of said door for a predetermined period of time after cessation of firing.

7. In an aircraft having a port opening for a gun, a door for said opening, and actuating means for said door comprising spring means constantly urging said door to open position, motordriven worm and gear means for closing said door and tensioning said spring, and means for disengaging said worm from said gear for permitting said spring to open said door.

8. In an aircraft having a port opening for a gun, a door for said opening, actuating means for said door, means for preventing operation of said actuating means, and locking means on said aircraft connected to said operation-preventing means and actuated by the weight of the aircraft when on the ground to prevent closing of said door when said aircraft is on the ground.

9. A device as recited in claim 8 and further including means responsive to operation of said locking means for automatically closing said door when said aircraft is airborne.

10. In an aircraft having a gun provided with a blast tube, a forward extension on said blast tube, an opening in said extension for said gun, a door for said opening, lever means pivotally connected to said door, a housing for said lever means opening into said extension, means for actuating said lever to operate said door, and means for sealing said actuating means with respect to said housing.

GEORGE BUSSIERE.

QUINTON C. JOHNSON.

JOSEPH E. STRAUB.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,186,023 Moore June 6, 1916 1,298,886 Challenger Apr. 1, 1919 2,173,273 De Seversky Sept. 19, 1939 2,340,705 Slate Feb. 1, 1944 2,385,051 Berlin et a1 Sept. 18, 1945 2,402,065 Martin June 11, 1946 2,409,637 Lucht Oct. 22, 1946 2,428,359 De Permentier Oct. '7, 1947 2,445,235 Myers July 13, 1948 FOREIGN PATENTS Number Country Date 804,838 France Aug. 10, 1936 560,167 Great Britain Mar. 23, 1944 

